摘要：选取三亚湿地1995、2000、2005、2010、2015和2020年6个时间节点,利用Landsat遥感影像为主要数据源,采用景观动态分析方法,并选择适当的景观格局指数,分析三亚湿地景观的空间格局变化及其影响因素。结果表明:三亚市的湿地面积从1995年的18.39 km^(2)减少至2020年的13.85 km^(2),减幅达25%;在2000—2005、2005—2010年减幅明显,其动态度分别为-1.92%和-2.76%,2015年后减速趋缓,动态度为0.01%。2015—2020年湿地面积持续扩大,斑块优势度增大,斑块的形状和边缘效应更加复杂,但景观空间格局的聚集性呈现出减弱的趋势,复杂性也明显降低,景观连接度有所增强,破碎化程度却呈现出加重的趋势。社会经济因素是造成三亚市湿地空间变化的主要因素,其中人口增长、城市扩张、湿地空间被不断压缩是导致全市湿地面积减少且破碎度增加的主要原因。但是随着国家相关政策的出台,人们对湿地保护意识的增强,三亚市湿地的生存环境在改善中。

摘要：通过样本学习得到的目标先验视觉信息可以对目标进行高效表示,在目标跟踪中通过充分利用这些先验知识提高跟踪精度。基于此,提出一种利用离线训练结果进行在线跟踪的算法,首先利用深度神经网络通过样本学习目标的视觉先验,然后跟踪在贝叶斯推理框架下进行,在跟踪过程中将目标视觉先验用作目标的外观表示,跟踪结果由粒子滤波顺序得到。为了防止跟踪漂移,通过特征点匹配建立系统的状态模型,并且将目标分解成子目标进行相似度量,提高算法抗局部遮挡能力。在多个公开测试集上实验表明,该算法可以提高目标跟踪精度,防止跟踪漂移,实现长序列可靠跟踪。

摘要：单目视频下的人体三维运动跟踪过程中,二维肢体模板由于遮挡而无法配准,从而造成跟踪丢失。针对这一问题,建立人体肢体的三维纹理模型用于人体运动跟踪。首先在初始帧中得到纹理模型在直立姿态下的二维模板及各像素点的局部坐标,在其它帧中利用像素灰度一致性约束优化进行跟踪,同时由跟踪结果生成新的二维模板,形成一个模板库。随着跟踪帧数增加,模板库动态更新,最终跟踪结果由模板库中各模板配准结果中的最优值决定。实验结果表明,与单一二维模板配准算法相比,多模板匹配能够克服由于肢体自旋转而造成的遮挡,取得了更好的跟踪结果。

摘要：The role of carbodiimide as dehydrant in the chemo‐,regio‐and stereoselective Pd(Ⅱ/0)‐catalyzed hydrocarboxylation of various alkynes with HCOOH releasing CO in situ is reported for the first time to obtainα,β‐unsaturated carboxylic *** symmetrical and unsymmetrical monoalkynes show good ***,2,2’‐(1,4‐phenylene)diacrylic acid can also be synthesized in high yield through the dihydrocarboxylation of 1,4‐***,an excellent result in gram scale experiment and TON up to 900 can be obtained,displaying the efficiency of this ***,regulating the types and concentrations of dehydrant can control the CO generation,avoiding directly operating toxic CO and circumventing sensitivity issue to the CO *** the basis of the attractive features of formic acid including easy preparation through CO_(2) hydrogenation and efficient liberation of CO,this protocol using formic acid as bridging reagent between CO_(2) and CO can be perceived as an indirect utilization of CO_(2),offering an alternative method for preparing acrylic acid analogues.

摘要：Mountain tunnel crossing a normal fault in seismically active zone is easily affected by normal fault slip and earthquake. It is necessary to study tunnel dynamic response under action of normal fault slip and earthquake. In this paper, a three-dimensional normal fault sliding device was designed, and a shaking table test was carried out to study tunnel seismic performance under normal fault slip. The results show that peak acceleration of lining is dominated by an existence of fault and direction of seismic excitation, not normal fault slip. And the incremental strains of lining in critical zone with 1.7 times fault thickness and centered in faults induced by normal fault slip and seismic excitation are larger than ones only by seismic excitation. And the incremental strains in critical zone increase with the increase of normal fault slip magnitude ranging from 0 to 2 mm. And normal fault slip results in a significant reduction of overall tunnel stiffness subjected to an earthquake. These experimental results provide a scientific reference for prevention and control measurement of tunnel damage under earthquake and normal fault slip.

摘要：Active-phase engineering is regularly utilized to tune the selectivity of metal nanoparticles （NPs） in heterogeneous catalysis. However, the lack of understanding of the active phase in electrocatalysis has hampered the development of efficient catalysts for CO2 electroreduction. Herein, we report the systematic engineering of active phases of Pd NPs, which are exploited to select reaction pathways for CO2 electroreduction. In situ X-ray absorption spectroscopy, in situ attenuated total reflection-infrared spectroscopy, and density functional theory calculations suggest that the formation of a hydrogen-adsorbed Pd surface on a mixture of the α- and β-phases of a palladium-hydride core （α＋β PdHx@PdHx） above -0.2 V （vs. a reversible hydrogen electrode） facilitates formate production via the HCOO intermediate, whereas the formation of a metallic Pd surface on the β-phase Pd hydride core （β PdHx@Pd） below -0.5 V promotes CO production via the COOH＂ intermediate. The main product, which is either formate or CO, can be selectively produced with high Faradaic efficiencies （〉90%） and mass activities in the potential window of 0.05 to -0.9 V with scalable application demonstration.

摘要：This study was conducted to reveal the effects of silicon(Si) application on nutrient utilization efficiency by rice and on soil nutrient availability and soil microorganisms in a hybrid rice double-cropping planting system. A series of field experiments were conducted during 2017 and 2018. The results showed that Si nutrient supply improved grain yield and the utilization rates of nitrogen(N) and phosphorus(P) to an appropriate level for both early and late plantings, reaching a maximum at 23.4 kg/ha Si. The same trends were found for the ratios of available N(AN) to total N(TN) and available P(AP) to total P(TP), the soil microbial biomass carbon(MBC), microbial biomass nitrogen(MBN), microbial biomass phosphorus(MBP), and the ratios of MBN to TN and MBP to TP, at different levels of Si. Statistical analysis further revealed that Si application enhanced rice growth and increased the utilization rate of fertilizer due to an ecological mechanism, i.e., Si supply significantly increased the total amount of soil microorganisms in paddy soil compared to the control. This promoted the mineralization of soil nutrients and improved the availability and reserves of easily mineralized organic nutrients.

摘要：观念广告是通过明确表达某种思想观点来吸引消费者的一种广告形式。因其包含丰富的思想而对受众的意识和行为产生深刻影响,所以研究观念广告中所呈现的价值观具有重要意义。文章从案例库抽取了93个观念广告作品,通过文本分析,把观念广告中所呈现的价值观分为5大类、19个主题。总体来说,我国观念广告所呈现的价值观是积极的、正面的,并具有选择性、公益性和现代性等特点。

摘要：针对目前产品设计与仿真分析系统之间的信息难以共享与重用,影响仿真效率等问题,提出了产品设计与仿真的集成信息模型与异构信息转化技术。分析了产品设计与仿真集成信息模型的结构组成,研究了三维几何建模系统、多体动力学系统、有限元分析系统,以及知识管理各系统之间的信息集成和数据转化技术,实现了产品设计与仿真分析的综合信息的集成。该方法已在产品开发中得到应用。

摘要：在深入研究现有可信移动平台设计方案和TCG移动可信模块相关技术的基础上,提出了带有移动可信模块的可信移动平台设计方案.平台采用基带处理器和应用处理器分离的结构,利用移动可信模块构建了以应用处理器为中心的可信区域,为移动平台提供受保护的计算和存储空间,提高了移动平台的安全性、灵活性和可靠性.分析了现有可信移动平台安全引导过程安全漏洞,提出了改进的安全引导过程,并通过谓词逻辑对改进的引导过程进行了正确性验证.